Electrometer



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' F. R. SOMMER.

ELECTROIVIETER. APPLICATION FILED JUNE15| I920.

Patented May/23,1922.

2 SHEETS-SHEET l.

F. R. SUMMER. ELECT ROMETER. APPLICATION FILED JUNE 15. 1920.

1 41% 1 1%., Patented. May 23, 1922. v

2 SHEETS-SHEET 2.

and hasspecial reference to improvements n n it. t une rather n FRED$OMMEIE, 0F EBOQKLYN, NEW" YORK.

ELECTROMETER.

iriam.

specification of Letters Patent.

Patented May 23,

Application filed .Tune 15, 1920. Serial No. 389,109.

To all whom it may concern:

lie it known that l, Finn) lit. lrloMMnR, citizen of the United States,residing at Brooklyn.,in the count y of Kings and State of New Yorlchaveinvented certain new and useful Improvements in lillcctrometers, ofwhich the following is as ieciiication.

This invention relates to clectroineters,

therein for accurately adjusting the pole plates and tensioning themetallic conductor positioned between the pole plates.

A primary object of the invention is to provide meansior expeditiouslyadjusting the pole plates to the desired position with reference to thequartz fibre or other metallic conductor with a great degree ofprecision, to thereby insure the accuracy and reliability ot the resultssought to be obtained through the use of this kind of instrument. Inthis connection the invention aims to elimintaate springs and otherelements which are likely to become inaccurate under constant use, andwhich through fractional defections from the normal standard frequentlyvary the conclusions and data observed from the functioning of themetallic conductor under the influence of an electrical circuit. i i

A further object of the invention is to provide a sale and reliablesupporting unit for the quartz fibre or other conductor, which not onlyfacilitates the initial assembly of the same in position, but alsopermits of such adjustment thereof as desired to place the said wireunder the proper tension.

With the above and other objects in view which will, more readily appearas the nature of the invention is better understood, the same consistsin the novel constructiomconn. bination. and arrangement of partshereinafter more :tully described, illustrated and claimed. j

A. preferred and practical embodiment of: the invention is shown in theaccompanying drawings, in which lligure 'l is an elevation, partly insection illustrating the improved. adjustable pole plate support and thetensioning device for the metallic conductor.

Figureil is an enlarged detail sectional view of the novel means ofadjustment for tensioning the quartz 'fibre.

Figure 3 is an enlarged detail view of the tensioning device shown inFigure 2.

Figure 4 is a detail plan view of the plate which carries the bridgewire, showing the type oi slot utilized in connection with the holdingpin.

Similar reference characters designate corresponding parts throughoutthe several figures of the drawings.

llllectrometers which are used for measuring the potential difference inelectrical currents by the attraction or repulsion of statically chargedelements require accurate and reliable adjustments to obtainsatisfactory results, and to this end the present invention hasparticularly in view novel and improved means for adjusting the poleplates of the divice as well as a novel tensioning device forpositioning the metallic conductor between the pole plates. Accordingly,as will be observed from the drawing the housing or casing 1 which issupported on a suitable stand or base Qhas mounted in its side walls 2and 3 the novel adjustable pole plate units A and B respectively. Theseunits are of duplicate construction and therefore a description of onewill suiiice for the other.

Referring to the unit B for instance, which is shown in section inFigure 1 it will be observed that the same includes a supporting shaft4: provided with a clamping socket 5 adapted to receive the insulatedbushing 6 of the pole plate 7. This pole plate 7 may be electricallyconnected with a suitable source of curent through the wire connection 8and occupies a vertical position within the casingparallel to theoposite pole piece 7. And, for the purpose of securely holding the saidpole plate 7 in position within the socket 5, a suitable clamping screw5 may be utilized.

The said supporting shatt 4: mounted to be shifted horizontally tor thepurpose of quartz fibre or metallic conductor wire W.

and tofacilitate the accurate adjustment of the said supporting shaft,the same is adapted to have a tree sliding movement within the smoothbore 9 otthe tubular bearing member 10. This bearing member 10 isprovided with the attaching flange 11 for being secured to the wall ofthe casing, and is also provided in. its side wall with a slot 12 whichconstitutes a guide for the nut element 13 carried by the shaft 4:through the medium of the fastening 14 or its equivalent. By reason ofthe engagement of the nut within the slot 12 it will be apparent thatthe shaft 1 will have a true rectilinear movement in the bore 9 ot thesupporting member, and in. order to enable this movement to beexpeditiously and accurately e'l'lected the threaded portion 15 of theshaft lwhich pro-- jects beyond the end of the member 10 carries anadjusting nut 16 which is provided with an annular holding groove 17that is adapted to receive the flanged end 18 oi a check plate 19carried by the outside of the tubular member 10. With this arrangementit will be apparent that the adjusting nut 16 will be held relativelystationary with reference to the tubular member 10 so thatwhen itisturned it will cause the longitudinal shitting of the shaft 4:. And,for the purpose of preventing the shaft & from moving too far inwardlyand thus breaking the quartz fibre or filament, he same carries a stopnut 20 which in the arrangement shown consists of a screw threaded.shank portion for fitting into the socket 21 in the shaft and having theflange 22 for engaging with the head of the nut 16 to constitute thedesired abutment or stop.

Inconnection with. this portion of the apparatusit will therefore beapparentthat the invention aimsto provide a novel pole supporting unitwhich essentially consists of the tubular hearing member 10 and theshaft 4: carrying the pole plate 7, the said sha'tt being engaged by thenut 16which is rotatably held in a relatively fixed position whereby itsrotation permits the shifting of the shaft to the desired degree. Inthis feature of improvement it is to be observed that the check plate 19is important since it holds the nut 16 in a relatively fixed positionthough permitting of its rotation to propel the shaft -:l-. Also, themember 10 may be provided with a scale 5 for cooperating with the zeroline on the nut 13, and to check with this scale S another scale S maybe placed on the rim of the feed nut 16 this latter scale reading from azero mark on the member 10.

A further feature of improvement resides in the tensioninp' device formounting the wire between the pole plates. This device includes in itsorganization a post 23 which is held in the guide-web 24 in such amanner that it may be freely shifted in the direction oi its axis and tothis end the top 25 thereof is preferably reduced and threaded to engagewith the threaded bore 26 ot the adjusting nut 2'7 as clearly shown inFigure The said ad iustii'lg nut 27 is provided with an in'toriorlythreaded socket 28 for receiving a suitable cap 29 for housing the upperthreaded end of the post 23. and the sleeve portion 30 of said nut ispreferably externally threaded at 31 for a suitable distance of itslength to receive the lock nuts The arrangement here described thereforepermits ot the manipulation oi the nut 9/ in such a manner as to causethe longitudinal shifting of the post 23 while the nut ilscll' remainsin a fixed position within the top wall T of the casing. For the purposeof enabling the operator to accurately know the extent of movementgivei'i the {)USll through the manipulation of the nut the exposed facethereoi is preferably provided with a scale marked in suitable units otlcugth.

The lower end of the post :23 rigidly carries therewith the oilset arm81-3 which is provided with a slot 34: tor rccciving a post 35 carriedby the floor i of the casing to prevent the shifting ot the said oll'sctarm out of its proper position. The showing of the slot 3 1 in Figure 2would give the inn pression that some play might bc pcriniticd betweenthe arm and post but it is pointed out that the slot longer than it s\vidc .l'or the purpose oit' facilitating assembly. and that the widthof the slot is just enough to clear the pin 35 without pc1'mittin; anyappreciable side motion.

The outer endot the oll'set arm 33 (:Hl'ltH a novel wire su iiportingunit which includes the bushing 36 having the central bore I)? and thethreaded portion $38 for littiug into the arm. The said bore 37 of thebushing 36 is adapted to receive the stem 21$) o'l a clamping pin havinga head 4H) for engaging with the cross bar -11 which carries the anchorposts 4-52 at opposite ends thereof 'lor tho bridge wire 4- to which oneend ol the test wire W is attached. A. novel and distinctive feature ofimprovement in connection with the mounting of the holding pin withinthe bore 3'? is that the stem 33$) 01 said pin is provided with a recesshaving an inclined wall 45 which cooperates with a sct screw -16 in sucha manner that the tightening of the said screw will have the eil'ect ofpulling the stem 39 downwardly through the born to thereby cause thehead ell) ot the pin to firmly clamp the plate -11. in engagcincnt withthe upper surface of the arm 33.

The bridge wire .113 which is carried by the post may be soldered orotherwise secured thereto, and since this fastening operation isperfomed outside ol the apparatus and the wire is positioned bel'orcasscn'lbly it is desirable to provide the plate ll with a suitable slot4] For rccciving the stem or shank oi. the holding pin as will bcreadily apparent.

For the purpose of preventing the shift ing of the post 23 to such adownward posi tion as would cause the breaking ol the wire W a suitableadjustable abutment or stop 18 may be employed. This abutment ispreferably in the form of a screw 1-9 having the lock nut 50 thereon forthe purpose of facilitating setting at any desircd point while the upperend 51 thereof is adapted to engage directly with the end of the post23.

From the foregoing it will be apparent that the present inventionprovides a simple and novel type of pole plate carrier which is capableof facile adjustment without interfering with the metallic conductor,while at the same time adequate means is provided for adjusting thetension of the metallic conductor through the manipulation of the nut 27which causes i the shifting of the post 23. Also the replacement andremoval of the wire Wand may be readily effected through the provisionof the novel holding unit which involves the pin 39 that is engaged bythe set screw 46. I

"Wifliout further description it is thought that the many featuresandadvantages of the invention will be readily apparent, and it will ofcourse be understood that changes in the form, proportion and minordetails of constr urtion may be resorted. to without departing from thespirit of the invention or scope of the appended claims.

I claim:

l. In an electrometer, the combination with the casing and the testwire, of a pair of pole plate units carried by the sides of the casing,each unit including a tubular support, a pole plate carrying shaftadjustable therein, means for accurately shifting the pole platecarrying shaft, and means for preventing the movement of the same beyonda predetermined inward limit.

2. In an electrometer, the combination with the casing and the testwire, of a pair of pole plate units carried by the sides of the casing,each unit including a relatively shiftable shaft having a socket at oneend,

a pole plate having an insulating bushing for fitting in the socket ofsaid shaft and maintaining the said pole plate at right angles to theshaft, a feed nut for shifting said shaft in the direction of its axisto vary the distance of the pole plate from the test wire, and means forpreventing the shifting of the said shaft beyond a predetermined inwardlimit.

3. In an electrometer, the combination with the casing and the testwire, of a pair of pole plate units carried by the sides ofthe casing,each. unit including a relatively shiftable shaft having a socket in oneend and threaded at the other, a pole plate disposed at right angles tothe said. shaft and having an insulated support in the socket thereof, atubular casing for receiving said shaft and having a guide slot, a guidemember carried by the shaft and riding in said slot, a feed nut elementengaging with the threaded portion of the shaft, means for holding saidfeed nut in a relatively fixed position at the end of the tubularmember, and a stop element carried by the extremity of the shaft forengaging with the nut to prevent inward movement of the shaft beyond apredetermined limit.

4. In an electrometer, the combination with the casing and the testwire, of a pair of pole plate units carried by the sides of the casing,each unit including a tubular supporting member, a pole plate carryingshaft having threads thereon, a feed nut engaging with said threadedportion of the shaft, and means carried by the tubular member andengaging with the nut for holding the latter in a relatively fixedposition, and a stop member adjustal'ily engaging with the end of theshaft projecting beyond the nut and constituting a stop abutment toprevent movement of the shaft beyond a predetermined inward limit. i i

5. In an electrometer, the combination with the casing and the testwire, of apair of pole plate units carried by the sides of the casing,each unit including a tubular supporting member, a pole plate carryingshaft lnwing threads thereon, a feed nut having an annular groove, and aflanged holding plate screwed to the tubular member and having theoffset flange portion thereof engaging inthe groove of the nut, and arela tively adjustable abutment stop carried by the end of said shaft.

6. In. an electrometer, the combination with the casing, a test wire, asupport for one end of the test wire and means for engaging the otherend of the test wire for adj ust ing the tension thereof, said meansincluding a post adjustably supported by the easing, an off-set armcarried by the post, means carried by said arm for engaging with the endof the wire opposite the end connected with said support, and meanscarried by the casing for adjusting said post in the direction of theaxis of the test wire.

7. In an electrometer, the combination with the casing and the testwire, of means for adjusting the tension of the test wire including apost arranged in a plane parallel to the test wire and having a threadedupward end portion, a feed nut carried by the casing and engaging withthe said threaded portion of the post to adjust the same in thedirection of its axis, an adjustable stop abutment carried by the casingand adapted to abut against the end of the post to prevent movementbeyond a predetermined point, an off-set arm carried by the post, meansfor preventing the lateral movement of the arm, and a bridge wire unitdetachably carried by the outer end of the off-set arm and conhectedwith the test wire. I

8. In an electrometer, the combination with the casing and the testwire, of means for adjusting the tension of the test wire ineluding apost arranged in a plane parallel to the test wire. and having athreaded end. portion, a feed nut engaging with said threaded endportion of the post and having an externally threaded sleeve portion,lock nuts carried by the sleeve portion of the feed nut to maintain thelatter relatively fixed with respect to the-casing, an elf-set armcarried by the said post, and means carried by the oft-set arm forengaging with the test wire.

9. In an electrometer, the combination with the casing and the testwire, of means for tensioning the test wire including a relativelyshittable post having an off-set arm, a hollow bushing fitted to saidarm, a slotted cross bar having upstanding anchor posts at opposite endsthereof, a bridge wire screwed to the said upstanding anchor posts andconnected with the test wire, and a holding pin for detachably screwingthe cross bar within the bushing.

10. In an eleetrometer, the combination with the casing and the testwire, of means for tensioning the test wire including a rel ativelyshi-ftable post having an offset arm,

the recess in the shank of the pin to wedge the head of the pin inclamping: engagement with the cross bar.

In testimony whereof I hereunto a llix my signature in the presence oftwo witnesses. FRED l-l. SUMMER. \Vitnesses EMORY L. Gnorr,

A. J. Coornn.

